use askama::Template;
use askama_derive::Filter;
use chrono::Utc;
use std::collections::BTreeMap;

use invoice_generator::{group_by_customer, read_csv_file, Customer, Transaction};

#[derive(Template)]
#[template(path = "index.html")]
pub struct IndexTemplate {
    pub customers: Vec<(String, Customer)>,
    pub batches: Vec<String>,
}

#[derive(Template)]
#[template(path = "customer.html")]
pub struct CustomerTemplate {
    pub customer: &Customer,
    pub batches: Vec<String>,
}

pub fn calculate_card_totals(transactions: &[Transaction]) -> (f64, f64) {
    let total_amount: f64 = transactions.iter().map(|t| t.amount).sum();
    let total_volume: f64 = transactions.iter().map(|t| t.volume).sum();
    (total_amount, total_volume)
}

pub fn calculate_grand_total(customer: &Customer) -> f64 {
    customer
        .cards
        .values()
        .flat_map(|t| t.iter())
        .map(|t| t.amount)
        .sum()
}

pub fn format_amount(amount: f64) -> String {
    format!("{:.2}", amount)
}

pub fn format_volume(volume: f64) -> String {
    format!("{:.2}", volume)
}

pub fn format_date(date: &chrono::NaiveDateTime) -> String {
    date.format("%Y-%m-%d %H:%M").to_string()
}

pub fn now_string() -> String {
    Utc::now().format("%Y-%m-%d %H:%M").to_string()
}